The present invention relates generally to clamping components for holding workpieces in place, and is particularly directed to clamping components for holding workpieces having through-holes. The invention will be specifically disclosed in connection with a hydraulically actuated clamping module which extends through a through-hole.
In order to machine parts to finished dimensions, the parts must be accurately and securely held in place. This typically involves clamping the part on the machine tool. Since parts come in all sizes and shapes, securing the parts frequently presents a unique challenge for each part.
To produce a part efficiently, the cutting tool needs as much unobstructed access as possible in order to remove material from the part. Although it is common in industry to secure these parts on fixtures using standard modular clamping components, such components sometimes obstruct or reduce direct access to the areas on the part that have to be machined. Often, multiple clamping components are used, adding to complexity and reducing efficiency.
Additionally, in order to keep the time required to machine parts at a minimum, clamping components must make it easy and quick to unclamp a machined part and clamp the next part. The set up time required to switch from part to part also needs to be at a minimum. To some extent, the use of modular clamping components which are mounted to or in a fixture body has reduced the time required for set up. However, clamping components to date have not completely and adequately addressed all of the problems with unobstructed access to the areas to be machined, the time required to load and unload parts and for set up.
The present invention addresses these problems by eliminating and replacing the use of multiple individual modular clamping components on fixtures for parts with through-holes. The present invention, a modular expanding pullback clamp, provides greater access for cutting tools to engage the part, while also making the loading and unloading of parts by the machine operator straight forward and relatively easy. Parts with through-holes (whether entirely through the part, or just into a cavity large enough to permit use of the present invention) can be easily positioned, clamped and secured on a fixture by the expanding pullback mechanism of the modular hydraulic clamp.
It is an object of this invention to obviate the above-described problems and shortcomings of the prior art heretofore available.
It is another object of the present invention to provide a clamping module which provides maximum unobstructed access to a workpiece while securely holding the workpiece.
It is yet another object of the present invention to provide a clamping module which can easily accommodate various configurations of workpieces.
It is another object of the present invention to provide a clamping module on which it is easy to load and unload parts.
It is still a further object of the present invention to provide a clamping module which can radially and axially hold a workpiece.
It is yet a further object of the present invention to provide a clamping module in which pressurizing a single hydraulic chamber effects radially and axially clamping of a workpiece.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, there is provided a clamping module having a retractable drawbar and pivoting expansion members. The expansion members are pivotable from a first position having an effective diameter which is less than the minimum diameter of the workpiece hole through which the drawbar and expansion members are extended and a second position engaging the workpiece so as to transmit an axial force from the drawbar through the expansion members to the workpiece sufficient to secure the workpiece.
In accordance with another aspect of the present invention, the clamping module includes an expandable collet which, when expanded, applies a radial outward force to the workpiece so as to secure it radially.
In another aspect of the present invention, the drawbar, expansion members and expandable collet are actuated by supplying hydraulic pressure to a single chamber within the body of the clamping module. In accordance with another aspect of the present invention, the pivotable expansion members are engaged at one end by a frustoconical cylinder which resiliently urged there against so as to urge the pivotable expansion members radially inwardly.